Kagemusha,
I posted that account because it is the one that goes into greatest detail regarding the tribes, however it is quantified in most of the literature (if not all) that covers the rise of the Mongol empire under Chingis. It is to Jochi's credit that he managed this while only in his twenties

Jochi had proved himself to be a very able general, later he figured prominently during the invasion of Khwarazm, where he was given the most difficult objective. He was more compassionate than his father or brothers and during the mass destruction and killings that followed in Khwarazm, carried out by his father and Tolui in particular, he took his troops north to his Ulus (the land he had been granted) in open defiance; he had been vociferous over what he felt was unnecessary brutality and had argued with his brother, Chagadai.
He had learnt his skills as a commander under the guidance of Jebe and he knew the wisdom of negotiation. The forest people had been subjugated without warfare, through skillful diplomacy and it was this in particular that Chingis Khan commended him for

.......Orda